Methods for containing liquid materials and maintaining part alignment during assembly operations

ABSTRACT

Components may be interconnected using liquid materials such as liquid adhesive and solder. To prevent undesired movement between the components during the assembly process and to prevent the liquid material from flowing into undesired areas, an attachment and dam structure may be provided. The structure may be formed from a substrate such as a flexible polymer film coated with adhesive. When interposed between first and second components, the structure attaches the first and second components and prevents movement between the first and second components. The structure may have one or more edges adjacent to the liquid material to block the liquid material from flowing while the liquid material is in its liquid state. Once the components have been connected, the liquid material can be solidified.

This application is a division of patent application Ser. No.12/753,005, filed Apr. 1, 2010, which is hereby incorporated byreference herein in its entirety. This application claims the benefit ofand claims priority to patent application Ser. No. 12/753,005, filedApr. 1, 2010.

BACKGROUND

Liquid adhesive and solder are used in forming mechanical and electricalconnections in a variety of contexts. For example, liquid adhesive maybe used to attach parts together within an electronic device. Solderconnections may be formed when it is desired to mount a component to aprinted circuit board.

It can be challenging to properly control liquid materials duringmanufacturing. Liquid materials such liquid adhesives and solder thatare not well controlled may intrude into undesired portions of aworkpiece. For example, a liquid material that is not properlycontrolled may wick into undesired areas between closely spaced parts.This excess material can then interfere with the desired operation of aproduct. Attempts to reduce undesired movement of intrusions of liquidmaterials by reducing the volume of liquid material that is used aresometimes counterproductive. Solder joints that are formed without usingsufficient solder may be unreliable or may not exhibit satisfactorylow-resistance electrical connections. Adhesive joints that are formedwithout using sufficient liquid adhesive may be weak.

To address these concerns, solder dam and glue dam structures have beendeveloped. These structures use features such as ridges to block theflow of liquid materials during assembly operations and thereby containadhesive and solder in desired areas.

During assembly operations that involve that involve the use of liquidmaterials, undesired movements of workpiece parts relative to oneanother should be avoided. If parts are allowed to move with respect toeach other before an adhesive or solder joint has been properly formed,the parts may become permanently misaligned. Unintended movement duringassembly is sometimes addressed by providing parts with alignmentfeatures such as alignment posts and holes.

Strips of double-sided adhesive tape have been used in conjunction withepoxy when mounting display cover glass panels to housing structures incellular telephones. In this type of arrangement, rectangular pieces ofdouble-sided tape are used at the upper and lower ends of the display. Aperipheral bead of epoxy that is sandwiched between the panels and thatis separated from the double-sided tape by a raised housing ridge isused in mounting the panel. In this type of scenario, the double-sidedtape does not constrain the flow of the epoxy. Conventional damstructures may help prevent undesired adhesive movements, but do notprevent relative movement between parts before a finished adhesive bondhas been formed. This can lead to parts that are tilted or otherwisemisaligned with respect to each other.

It would therefore be desirable to provide improved ways in which to useliquid materials in the assembly of parts during manufacturing.

SUMMARY

Components may be interconnected using liquid materials such as liquidadhesive and solder. For example, a trim member may be attached to thesurface of a camera module using liquid adhesive or an electroniccomponent may be mounted to traces on a printed circuit board usingsolder.

To prevent undesired movements between the components during theassembly process and to prevent the liquid material from flowing intoundesired areas, an attachment and dam structure may be provided. Thestructure may be formed from a substrate such as a flexible polymer filmcoated with adhesive. The structure may have a shape such as a ringshape or other suitable shape. When interposed between first and secondcomponents, the structure attaches the first and second components andprevents movement between the first and second components. The structuremay have one or more edges adjacent to the liquid material thatconstrain the locations into which the liquid material can flow whilethe liquid material is in its liquid state. Once the components havebeen connected, the liquid material can be solidified.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional side view of a conventional camera module towhich a trim is being attached using adhesive.

FIG. 2 is a cross-sectional side view of the conventional camera moduleof FIG. 1 following attachment of the trim.

FIG. 3 is a perspective view of a component such as a camera module witha structure for constraining movement of liquid material and forensuring proper alignment between the component and another componentsuch as a trim piece during assembly in accordance with an embodiment ofthe present invention.

FIG. 4 is a cross-sectional side view of components of the type shown inFIG. 3 during assembly in accordance with an embodiment of the presentinvention.

FIG. 5 is a cross-sectional side view of another illustrativearrangement for containing liquid material and maintaining partalignment during assembly operations in accordance with an embodiment ofthe present invention.

FIG. 6 is a cross-sectional side view of an arrangement for preventingliquid material from intruding inwards into a given area between twoparts while maintaining alignment between the parts during assemblyoperations in accordance with an embodiment of the present invention.

FIG. 7 is a top view showing illustrative arrangements that may be usedfor constraining the flow of liquid material and maintaining partalignment during assembly operations in accordance with an embodiment ofthe present invention.

DETAILED DESCRIPTION

Electronic devices such as cellular telephones may contain cameras andother components. A camera may have a trim piece that is attached to acamera module base. In connecting components such as camera componentsand other parts in an electronic device, liquid materials such as liquidadhesive and solder may be used.

A conventional camera module to which a camera trim piece is beingattached is shown in FIG. 1. As shown in FIG. 1, camera module base 10contains camera components 30. Base 10 is typically formed from ahousing member such as a cube-shaped structure. Camera components 30include image sensor components, lenses, and other components. Cameracomponents 30 are aligned with opening 28 in base 10. A trim piece suchas trim 14 may be attached to base 10 (e.g., to provide the camera witha finished appearance). Opening 26 in trim 14 is aligned with opening 28to allow light to enter camera components 30. In a typicalconfiguration, openings 26 and 28 are circular in shape.

Trim 14 and camera base 10 have mating alignment features. As shown inFIG. 1, trim 14 has alignment posts 16 and camera base 10 hascorresponding alignment holes. Before inserting posts 16 into holes 18,drops of epoxy 20 are placed between upper surface 24 of camera base 10and opposing lower surface 22 of trim 14. Following insertion of posts16 into holes 18, epoxy drops 20 are compressed between surfaces 22 and24. This flattens epoxy 20 and forces epoxy 20 inwards against the ridgeedges 32, which serve as a glue dam, as shown in FIG. 2. Epoxy 20 isthen cured to bond trim 12 to housing 10.

Conventional camera assembly operations of the type shown in FIGS. 1 and2 rely on alignment features such as alignment posts and holes, whichcan add undesired complexity. Alignment features such as alignment postsand mating alignment holes are also generally not able to completelyprevent movement between the parts of a workpiece during assembly. As aresult, parts such as trim 14 of FIG. 2 may become tilted with respectto base 10 before the epoxy curing process is complete.

An arrangement for assembling components using liquid materials inaccordance with an embodiment of the present invention is illustrated inFIG. 3. As shown in FIG. 3, a first component (e.g., camera trim 36) maybe attached to a second component (e.g., camera module base 48) to forman assembled structure (e.g. camera 34, shown disassembled in theexploded view of FIG. 3). In general, any types of parts may beassembled using liquid materials. For example, structural parts such ashousing parts, frame structures, mounting brackets, component housings,and other mechanical parts may be assembled using liquid materials suchas liquid adhesive and solder. Electrical components may also beassembled using liquid materials. For example, an electrical componentthat has conductive terminals may be mounted to mating conductive traceson a printed circuit board using liquid materials such as liquidadhesive, liquid conductive adhesive, and solder. Liquid adhesivematerials that may be used for assembling components include epoxy andcyanoacrylate (as examples). Solder joints may be formed by meltingsolder or by depositing solder paste and reflowing the deposited pastein a reflow oven.

As shown in the example of FIG. 3, the components that are beingattached to each other may include a trim structure (trim 36) and acamera base structure (structure 48). In general, any suitableelectrical and/or mechanical components may be assembled using liquidmaterials. The attachment of a trim to a camera housing is merelydescribed as an illustrative example.

As shown in FIG. 3, trim 36 may have an opening such as circular hole38. Light may pass through hole 38 to lens 40 and other cameracomponents in camera base 48. Electrical components that may be used incamera base 48 include circuitry such as an integrated circuit imagesensor that converts received image light into digital image data.

Components such as components 36 and 48 may be formed from glass,plastic, metal, ceramics, or other suitable materials. Liquid material46 may be used in connecting components 36 and 48. Material 46 may be aliquid adhesive, solder, or other suitable material.

Liquid material 46 solidifies as part of the assembly process. Forexample, liquid adhesives such as epoxy are initially liquid, whichallows the adhesive to coat the surfaces of the parts being joined.Following application of the liquid adhesive to the parts of aworkpiece, the liquid is cured to form a completed bond. The curingprocess may involve application of heat (e.g., heat to maintain theworkpiece at room temperature or sufficient heat to raise the workpieceto an elevated temperature). Applying heat for a sufficient amount oftime will cause the liquid epoxy to solidify and form a stable bond.Some liquid adhesives are cured (and thereby solidified) by applicationof ultraviolet light (e.g., UV-cured liquid polymer adhesives such as UVepoxy). Combinations of heat and light can also be used to cure liquidadhesives.

Materials such as solder can initially be solid (e.g., solder wire), caninitially be applied as a paste, etc. During solder reflow operations,heat is applied (e.g., to raise the solder to a temperature above 200°C. or more). This causes the solder to melt and form a liquid. Theliquid solder flows over exposed metal parts such as the terminals onelectronic components and the associated exposed traces (solder pads) onprinted circuit boards during reflow operations. When reflow operationsare complete, the workpiece is cooled to room temperature and the soldersolidifies into a finished solder joint.

To ensure that trim 36 is held in a desired orientation with respect tohousing 48 while liquid material 46 is being hardened (e.g., by curingan adhesive or by cooling molten solder), structure 34 may be providedwith attachment and liquid dam structure 42. Structure 42 may be formedfrom a layer of double-sided tape or other material that serves toconnect components together. The shape of structure 42 may also allowstructure 42 to serve as a barrier to the flow of the liquid materialwhile in its liquid state. Structure 42 may therefore serve both as adam (i.e., a solder dam or glue dam) and as a attachment structure thatholds the workpiece together or at least prevents undesired movement ofworkpiece components during assembly (i.e., before the liquid materialenters its solid state). As part of the assembly process, additionalattachment mechanisms may be used to improve the strength of the bondbetween components in the workpiece. For example, the bond between thecomponents may be strengthened by use of the liquid material (e.g.,liquid adhesive).

Structure 42 may include a substrate. Layers of adhesive may be used inattaching structure 42 to the components of the workpiece (i.e.,components 36 and 48 in the example of FIG. 3). For example, ifstructure 42 is provided in the form of a thin disk-shaped member asshown in FIG. 3, adhesive may be provided on the upper surface ofstructure 42 to facilitate attachment of structure 42 and component 36and may be provided on the lower surface of structure 42 to facilitateattachment of structure 42 to component 48. The adhesive may be providedusing any suitable adhesive-dispensing technique (e.g., spraying,dipping, painting, pad printing, screen printing, etc.). Thesetechniques may be used to apply adhesive to the substrate of structure42, the surfaces of the workpiece, or both the substrate of structure 42and one or more surfaces of the workpiece. The substrate in structure 42may be formed from metal, plastic, ceramic, glass, composites, or othersuitable materials. The substrate may be rigid or flexible. Flexiblesubstrates may be used to conform to complex workpiece surfaces duringassembly.

With one suitable arrangement, structure 42 may be formed from a sheetof double-sided tape. The tape may have a substrate such as a thinflexible polymer sheet (e.g., polyimide, polyethylene terephthalate,etc.). The polymer sheet may have upper and lower surfaces that arecoated with adhesive. During assembly, movement of liquid material 46may be impeded by the presence of structure 40. For example, in thearrangement of FIG. 3, outer peripheral edge 44 of ring-shaped structure42 may prevent liquid material 46 from intruding onto lens 40 and otherstructures within the inner portion of structure 42. The substratematerial that is used in forming structure 42 may be chosen to resistexpected process temperatures. For example, if liquid material 46 issolder that is being heated to 240° C. (as an example), the substratematerial of structure 42 may be chosen to be capable of withstandingdamage when exposed to materials at temperatures of 250° C. or less.When liquid material 46 is in its liquid state, it flows up against edge44 and structure 42 and remains in this position, adjacent to edge 44and structure 42 when liquid material 46 enters its solid state (e.g.,when liquid adhesive cures or when solder solidifies).

Structure 42 may be attached to one or both of the components in aworkpiece by hand or using an automated positioning tool. As an example,structure 42 may be attached to the lower portion of apparatus 34 (i.e.,component 48) by hand (or using an automated tool) before an automatedtool (or hand assembly) is used in attaching upper component 36 tocomponent 48.

Consider, as an example, the use of the automated assembly system(system 50) of FIG. 4. As shown in FIG. 4, assembly tool 50 may includea computer-controlled actuator such as actuator 52. Actuator 52 may holdcomponent 36 and/or component 48, so that the position of component 36relative to component 48 may be adjusted. Tool 54 may have a controlunit such as control unit 54. Control unit 54 may include a computer orother suitable computing equipment that issues control commands foractuator 52. One or more cameras such as camera 56 may be used to gatherimages for control unit 54. Control unit 54 may use gathered image dataor other feedback to determine how to adjust the relative position ofcomponents 36 and 48 relative to each other. Once component 36 has beenaligned properly with component 48 (i.e., when camera 56 detects thathole 38 is aligned with lens 40 or when camera 56 detects that alignmentmarks or other alignment features on the workpiece components arealigned as desired), actuator 52 may be directed to press component 36downwards (in the FIG. 4 example), thereby compressing structure 42between the opposing surfaces of components 36 and 48 and forming anadhesive bond.

As shown in FIG. 4, structure 42 may include substrate 42B (e.g., aflexible polymer sheet that serves as a tape substrate) and adhesivecoating layers 42A and 42C. When components 36 and 48 are forcedtogether by actuator 52 (or by manual manipulation of the workpiececomponents), components 36 and 48 become attached to each other. Theshape of structure 42 also forms a dam that contains the movement ofliquid material 46. In the FIG. 4 example, liquid material 46 (e.g.,liquid adhesive) has been placed on the outside of structure 42.Structure 42 may have a ring shape as shown in FIG. 3). When components36 and 48 are pressed towards each other, liquid material 46 will flowalong the exposed surface of components 36 and 48, coating thesesurfaces in preparation for formation of a bond. The outer edge 44 ofstructure 42 prevents undesired movement of liquid material 46.

The adhesive nature of structure 42 serves to prevent undesired movementof components 36 and 48 relative to each other while liquid material 46is still in its liquid state. This ensures that components 36 and 48will not be misaligned laterally (horizontally in the view of FIG. 4)and will not be misaligned rotationally (tilted off of the horizontalaxis in the view of FIG. 4). Rotational and lateral alignment in otherplanes (i.e., a plane perpendicular to the page of FIG. 4) may also beensured.

While the positions of components 36 and 48 are fixed with respect toeach other by structure 42, tool 50 may form a solid out of liquidmaterial 46. Tool 50 may, for example, using bonding tool 58 to applyultraviolet light, heat, etc. Bonding tool 58 may use these techniquesto cure liquid adhesives and/or to reflow solder paste. Followingcooling to room temperature (if elevated temperatures were involved),the liquid material 46 will solidify (e.g., to form a properly alignedadhesive joint or to form a properly aligned solder joint).

As shown in the example of FIG. 5, structure 42 may have multiple partssuch as outer ring part 42-1 and inner ring part 42-2. This allowsliquid material 46 (e.g., liquid adhesive or solder) to be confined inmultiple dimensions. For example, by use of an outer ring and an innerring for structure 42, liquid material 46 may be confined to a ringshape having its outer edge bounded by inner edge 44-1 of outer ring42-1 and having its inner edge bounded by outer edge 44-2 of inner ring44-2.

FIG. 6 is a cross-sectional side view of a workpiece showing howcomponents 36 and 48 may be attached by a solid structure. Structure 42in the FIG. 6 arrangement has a solid shape (e.g., a circle or rectanglewhen viewed from direction 110) with a single outer edge 44 around itsperiphery. This type of structure may be used to prevent inward movementof liquid material 46.

FIG. 7 is a top view of an illustrative electronic device (device 80)showing different types of patterns that may be used for structure 42(which is shown as structures 42A, 42B, 42C, 42D, 42E, 42F, and 42G inFIG. 7). Device 80 may include a first component (e.g., a housingstructure or other suitable structure) and a second component (e.g., acover glass or other suitable structure) that are joined usingstructures such as structures 42A, 42B, 42C, 42D, 42E, 42F, and 42G andliquid material 46 (e.g., solder or liquid adhesive).

Structure 42A forms a rectangular ring that contains liquid material 46within an inner rectangular region.

Structure 42B forms a circular ring that prevents liquid material 46from entering interior area 88.

Structure 42C is an example of a rectangular ring that prevents liquidmaterial 46 from entering interior rectangular region 92.

Structure 42D is a rectangular ring that contains liquid material 46within its interior, so that the contained liquid material does not flowoutwards into exterior 96.

Structures 42E and 42F work together to form a ring-shaped containmentarea for liquid material 46. As illustrated by overflow structure 104,any of structures 42 may, if desired, be provided with shapes that helpaccommodate the flow of excessive liquid material 46. Overflowstructures may take the form of additional liquid reservoirs, wavyedges, etc.

Structure 42G is a solid central structure (as with the example of FIG.6) that prevents liquid material 46 from intruding inwardly.

The foregoing is merely illustrative of the principles of this inventionand various modifications can be made by those skilled in the artwithout departing from the scope and spirit of the invention. Theforegoing embodiments may be implemented individually or in anycombination.

What is claimed is:
 1. A method for assembling components, comprising:attaching a first component to a second component using a structure thatincludes a flexible substrate and adhesive; preventing movement of aliquid material using at least one edge of the structure; andsolidifying the liquid material against the edge of the structure. 2.The method defined in claim 1 wherein the structure comprises apatterned piece of double-sided tape.
 3. The method defined in claim 1wherein the liquid material comprises molten solder and whereinsolidifying the liquid material comprises cooling the molten solder toform a solder joint between the first and second components.
 4. Themethod defined in claim 1 wherein the liquid material comprises liquidadhesive and wherein solidifying the liquid material comprises curingthe liquid adhesive.
 5. The method defined in claim 4 wherein curing theliquid adhesive comprises heating the liquid adhesive.
 6. The methoddefined in claim 4 wherein curing the liquid adhesive comprises applyingultraviolet light to the liquid adhesive.
 7. The method defined in claim1 wherein the edge comprises an outer peripheral edge for the structure,wherein the liquid material surrounds the structure, and whereinpreventing movement of the liquid material comprises preventing movementof the liquid material using the outer peripheral edge.
 8. The methoddefined in claim 1 wherein the edge comprises an inner peripheral edgefor the structure, wherein the liquid material is surrounded by thestructure, and wherein preventing movement of the liquid materialcomprises preventing movement of the liquid material using the innerperipheral edge.
 9. A method for assembling first and second components,comprising: attaching a structure that has a substrate and adhesive toat least the first component, wherein the structure comprises anoverflow structure; placing a liquid material between the first andsecond components; collecting excess amounts of the liquid material inthe overflow structure while at least partly constraining movement ofthe liquid material using the structure; and solidifying the liquidmaterial.
 10. The method defined in claim 9 wherein the structurecomprises double-sided tape, the method further comprising attaching thefirst component to the second component using the double-sided tape. 11.The method defined in claim 9 wherein the liquid material comprisesliquid adhesive and wherein solidifying the liquid material comprisescuring the liquid adhesive.
 12. The method defined in claim 11 whereincuring the liquid adhesive comprises heating the liquid adhesive. 13.The method defined in claim 11 wherein curing the liquid adhesivecomprises applying ultraviolet light to the liquid adhesive.
 14. Themethod defined in claim 9 wherein the structure forms a ring-shapedbarrier and is configured to prevent the liquid material from flowinginto the ring-shaped barrier.
 15. The method defined in claim 9 whereinthe structure forms a ring-shaped barrier and is configured to preventthe liquid material from flowing out of the ring-shaped barrier.
 16. Amethod for assembling first and second components using liquid adhesive,comprising: placing the liquid adhesive between the first and secondcomponents; pressing the first and second components together; while thefirst and second components are being pressed together, laterallyconstraining movement of the liquid adhesive using a tape adhesive dam;and curing the laterally constrained liquid adhesive to attach the firstand second components together.
 17. The method defined in claim 16wherein the tape adhesive dam forms a ring-shaped barrier and whereinlaterally constraining movement of the liquid adhesive comprisespreventing the liquid adhesive from flowing into the ring-shapedbarrier.
 18. The method defined in claim 16 wherein the tape adhesivedam forms a ring-shaped barrier and wherein laterally constrainingmovement of the liquid adhesive comprises preventing the liquid adhesivefrom flowing out of the ring-shaped barrier.
 19. The method defined inclaim 16 wherein curing the laterally constrained liquid adhesivecomprises heating the laterally constrained liquid adhesive.
 20. Themethod defined in claim 16 wherein curing the laterally constrainedliquid adhesive comprises applying ultraviolet light to the laterallyconstrained liquid adhesive.